1. Field of the Invention
The invention relates to internal combustion engines for motor vehicles. More specifically, the invention relates a method for reducing white smoke and the start-to-idle time of internal combustion engines for motor vehicles.
2. Description of the Related Art
Fuel efficiencies and pollutants are two great concerns for consumers and environmental advocates alike. Thus, there is an almost continuous effort to increase efficiencies and reduce pollutants in the automotive industry. Internal combustion engines which combust diesel fuel take a greater time to reach an idle speed (in revolutions per minute) from a cold start than comparable spark ignition engines. This factor increases the consumption of fuel by such diesel powered engines. U.S. Pat. No. 5,465,701, issued to Hunt on Nov. 14, 1995, addresses the cold start issue for internal combustion engines in general. This reference discloses a fuel control system wherein a cold start fuel injector is mounted in an air intake passageway downstream from a throttle for the internal combustion engine. A three way air valve has an air inlet fluidly connected to the air intake upstream from the throttle. An engine control unit controls the actuation of the air valve and fluidly connects an inlet to a first outlet, a second outlet or both outlets. In addition, the air valve may close fluid communication between the inlet and the outlets. This device is undesirable because it introduces new hardware which must be coordinated with the operation of other necessary components of the internal combustion engine. More specifically, the fuel injector and the air valve must be coordinated such that the fuel injector and the air valve operate to reduce the amount of time it takes for the engine to reach an idling speed.
U.S. Pat. No. 5,492,100, issued to Ishii et al. on Feb. 20, 1996, discloses a fuel control device which prevents an internal combustion engine from using all of its cylinders except when a full cylinder operation mode can be reliably changed over from the partial cylinder operation mode. The valves are changed over using a control mechanism which selectively operates the valve change over. The valve change over is operated in a target operation mode selected by the operation mode selector. This patent does not, however, disclose the use of fuel ratios to minimize pollutants exhausted by an internal combustion engine fueled by diesel fuel that will reduce the amount of pollutants exhausted thereby.